Enzo250gto Posted December 30, 2015 Share Posted December 30, 2015 RebekahsZ is right about checking the tires first. I had fitted some 245/45/16 tires to my '76 260z on 16x8 BBS wheels and found that they tram tracked on every uneven section of the road. The tire shape was more of a sharp angle at the edges with a large footprint. On changing to a 225/50/16 profile tire which had more of a rounded edge to the footprint, it was like driving a different car. For a street car the narrower tire worked out better. For a race car on smooth tracks and without the suspension travel of a street car (which would be on all sorts of rough roads), you can obviously get away with wider tires. As to modifying the cross member or adding Bump steer spacers, well that is up to the individual. All the best for the New Year. David (Enzo) Quote Link to comment Share on other sites More sharing options...
TUME Posted December 30, 2015 Share Posted December 30, 2015 (edited) I have raised inner pick-up point over an inch. But that is different story because i have S13 knucles etc. I also raised whole crossmember, so it doesn´t affect bump steering. Main point was to archieve decent roll center height. It should be now about 3in above ground level. After that bump steering will deleted with tie rod end. In picture, control arm is close to it`s position when car is on wheels. Edited December 30, 2015 by TUME Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted December 31, 2015 Share Posted December 31, 2015 (edited) Plates are supposed to be 14g steel, but I couldn't find any so I used 1/8". Edited December 31, 2015 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted December 31, 2015 Share Posted December 31, 2015 Looks good. Except for the two picture that look like neck X-Rays. What is the side to side distance between your LCA mounting holes? How Long is the slot? Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted December 31, 2015 Share Posted December 31, 2015 (edited) Yeah, this was a suck job with my sore neck. Going Tuesday to talk to somebody about a steroid shot. I wish I could just have a neck transplant. C3PO seems to get one at the drop of a lightsaber. At least it isn't under the dash-I'm dreading putting gauges in this junker. I can't measure the side-side (horizontal) distance: the crossmember is installed in the car and I couldn't give you an accurate measurement. I used a plumb-bob and a bubble level to TRY to put them vertically the same spacing as the lower (stock) holes. Vertically, the drilled holes are centered 22mm above the original. The holes have a diameter of 14mm. So, I measured 29mm above the top edge of the bolt hole with a caliper and popped a divet with a center punch. So, the total length of the slot is 22mm + 14mm=36mm. I should have 22mm of vertical adjustment. I need to find a pair of new 14mm bolts (grade 10.9) that have the same shank length but a little longer threaded portion so I can run a thick washer on both sides of the crossmember...looks like a bunch of time searching on boltdepot.com ahead. Welder comes Saturday to weld the plates on. Cut the slots with a dremel tool laying on my back in the dark-wish they looked like a machinist did them, but they will have to do. I still have a long way to go....getting ready to do some on-line lift shopping-it was a good year at the office. The old office manager was over contributing to my 401K and the new office manager caught it and just gave me a big refund check that should just about cover it. If you need me to, I can go measure the center to center length of my TTT LCAs adjusted to their shortest dimension. They are in the trunk. I can only give you unassembled measurements of parts. Ask me what you want me to measure and I'll run out and do it to the best of my ability. Going to dinner and a movie in about an hour. Edited December 31, 2015 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
socorob Posted December 31, 2015 Author Share Posted December 31, 2015 Another question I have, which I'm not sure if this would vary between cars with different control arm lengths, is ...... is there an optimal angle the lca should angle down from horizontal, or a useful range? I know some point is too much and some point is not enough, but what would that range be? And on the subject of length, is it best to keep the front track width within a certain distance compared to stock? Quote Link to comment Share on other sites More sharing options...
zbloke Posted January 1, 2016 Share Posted January 1, 2016 I need to find a pair of new 14mm bolts (grade 10.9) that have the same shank length but a little longer threaded portion so I can run a thick washer on both sides of the crossmember...looks like a bunch of time searching on boltdepot.com ahead. When I had the same issue I took the OEM bolts to a machinist and had him reduce the thickness of the bolt head to increase the underhead length by the thickness of the two washers I wanted to fit Quote Link to comment Share on other sites More sharing options...
TUME Posted January 2, 2016 Share Posted January 2, 2016 Another question I have, which I'm not sure if this would vary between cars with different control arm lengths, is ...... is there an optimal angle the lca should angle down from horizontal, or a useful range? I know some point is too much and some point is not enough, but what would that range be? And on the subject of length, is it best to keep the front track width within a certain distance compared to stock? Bacically everything in suspension is compromice, some solutions are better than others, but not necessarily all ways. Are we talking about strut suspension. If so, within "normal" SAI-angles can be used angles somewhat zero and up. Or down, if you think about control arm. Remember measure angles by pivot points. Widening track affects weight tranfers, and by that spring load and wheel rate depending suspension type. Widening both ends same amount is a safe way. If you not sure what you are doing. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted January 7, 2016 Share Posted January 7, 2016 Bacically everything in suspension is compromice, some solutions are better than others, but not necessarily all ways. Are we talking about strut suspension. If so, within "normal" SAI-angles can be used angles somewhat zero and up. Or down, if you think about control arm. Remember measure angles by pivot points. Widening track affects weight tranfers, and by that spring load and wheel rate depending suspension type. Widening both ends same amount is a safe way. If you not sure what you are doing. Could not have said it better myself. Everything is a compromise. Especially with a strut suspension. You can really get wrapped around the axle looking for some perfection that is not there. And everything you change has at least a primary and secondary effect. So think about that when you start turning screws on those trick adjustable parts and drilling cross-members. But with that said, I don't think there are any negatives to getting rid of bump steer...... Quote Link to comment Share on other sites More sharing options...
johnc Posted January 7, 2016 Share Posted January 7, 2016 And all of this is meaningless until you get some lap times. Unless you can calculate exactly what your tires need from the car and you, adding adjustability is a good idea. Don't worry right now about the exact position of the inner LCA mounting point. Track testing and lap times will tell you where it needs to be and be prepared to make adjustments that go against all the advice on this site. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 7, 2016 Share Posted January 7, 2016 I was also reminded of a saying from the best hands on suspension and pro development race driver I know, "Don't let perfect get in the way of better." Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 9, 2016 Share Posted January 9, 2016 That's clean looking. Did the 7/8'' make a big difference? It was part of a lot of changes. Part of that was to reduce bumpsteer and have the arms closer to level when operating since the car was lowered. None of this was tested a single item at a time so take that into account for the lap time difference. The car was around a second faster on a 48 second lap (now 47). The bigger difference, as Jon mentions, is you could do that repeatedly and it wasn't so hard to drive. Cary Quote Link to comment Share on other sites More sharing options...
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